The development and implementation of the mass spectrometry core is essential to the research of the listed principal investigators. In particular the core will provide mass spectral analysis using the proposed bottomup and top-down methods employing both Q-TOF technology as well as FTICR high-resolution analysis. Both a top-down (intact protein identification) and a bottom-up (protein digestion) approach will be used to identify proteins of the various ribosomal complexes. Differences in post-translational modifications will be determined for ribosome complexes which have been subjected to infection by various viruses (hepatitis c, dengue, etc). eif3 factors associated with the ribosome will be analyzed and investigated for the presence of phosphorylation. Both the high-resolution capabilities of the exisiting FTICR and the sensitivity and flexibility of the Q-TOF, in combination with well established sample preparation methods such as IMAC, will allow for the unambiguous determination of protein constituents and associated post-translational modifications.